Multiple Sclerosis (MS)

Multiple Sclerosis for whatever reason is one of the few medical illnesses that are very well known by the public in abbreviation as “MS”! This is not because of its high prevalence or incidence, as it has a global prevalence of 30/100,000. But it is well known, perhaps due to its high prevalence in northern hemisphere, specially in Europe that has the rate of 80 per 100,000, compared to 8.3 and .5 per 100,000 in the Americas and Africa perspectively. It maybe perhaps also well known, due to its different presentations, from mild relapsing-remitting with almost normal life expectancy to the severe life-shortening progressive relapsing. Most importantly it is a mysterious disease with its varied clinical and symptoms presentation and more so, an enigma for the medical practitioners and scientist who still struggle to figure it out and treat it!

As it was discussed in “Autoimmune Disorders” here, MS is a very good and known example of such disorder, with systemic presentation like some others, e.g. Rheumatoid Arthritis (RA), but unique in having relapsing, remitting and progressive courses unlike others. From another perspective, the clinical manifestations and symptoms presentation of MS with its varied course is as such that its diagnosis could be quite evasive and easily not taken serious by the patients and the physicians. In fact MS before being labeled as such and being recognized as a neurological disorder by the founder of modern neurology, Jean Martin Charcot, it had been mistaken by predecessors as a hysterical reaction and a psychological disorder! The reason of such confusion is that MS can manifest with almost any neurological or even psychological signs and symptoms. These varied symptoms could cover autonomic, visual, motor and sensory nervous system and could include loss of sensitivity or changes in sensations, e.g. tingling, numbness, muscle weakness, spasms, difficulties in movements, coordination and balance, speech and swallowing problems, visual symptoms such as nystagmus, double vision, fatigue, chronic pain, electrical sensation feelings throughout the body, bladder and bowel difficulties, thoughts and emotional problems, depression and unstable mood among others.

More mysterious than its clinical presentation, is MS’ etiology, hence pathophysiology that its successful treatment all depending on. Unfortunately after almost one and half century of its diagnostic inception by Charcot, we are not yet conclusive in what is(are) the cause(s) of MS so to search for a cure. But the only available and relatively effective treatments for MS are basically laden within the arena of immune enhancers, such as interferons beta, monoclonal antibodies, etc. that all are good indication and evidence to the autoimmune nature of the disorder, caused by some microorganism insults. Association with human herpes viruses, specially Epstein Barr Virus (EBV) is strong as the risk of contracting MS in infected individuals are very high and in non-infected ones very low. Moreover the prevalence of the disease is the most common in northern hemisphere and minimal in equator regions in agreement with such viral geographic distribution. Despite some beliefs, MS is not purely a genetic or hereditary disease, as its concordance rate among non-identical twins is only 0.5% and among identical twins, only 2.5%. But the risk of developing the disease in children when both parents are affected is 10 times more of the general population. The genetic connection in MS is only through genetic susceptibility and increasing the risk of contraction through HLA (Human Leukocyte Antigen) and Major Histocompatibility Complex (MHC) systems that are again evidence to the autoimmune and micro-organismal invasion of the immune system.

Not just being born in northern hemisphere, particularly Europe, and specially in the winter months, where and when there is more chance of viral infections, such as with EBV, immigrating to such geographical regions before age 15 has also been shown to increase the risk of contracting the disease. In contrast emigration out of northern hemisphere to other regions past age 15 is not protective against contracting MS!

As it was discussed in the section of “Autoimmune Disordere” that MS truly and well belongs to, the viral insult through “molecular mimicry”, tricks the host immune system to recognize its own tissue as foreign, antigen or eiptope, and the occupying virus as the host, antibody or paratope. This deceives the immune system to produce HLA against its own tissues and in case of MS against the myelin sheath of the nerves and over time a major portion of brain white matter or trans-communication highways of the central nervous system (CNS). It takes the viral insult only few years to cause plaques in the CNS of the affected individual, and depending on the severity of the insult and the weakness of the patient’s immune system, causes different courses of the disease. But the impact is not ending within the affected individual, but continues through his next generations by affecting his genomes, e.g. HLA and MHC systems. This could be so that the next generations may still contract the disease even when have no similar viral infection, e.g. EBV, but through immune cross-reactivity and genetic susceptibility, when they have a different viral encounter, e.g. common viral infections such as measles, mumps and rubella!

Dr.Mostafa Showraki, MD, FRCPC                                                               Lecturer, University of Toronto,School of Medicine,Author: “ADHD:Revisited” Book “adhdrevisited.com”/”medicinerevisited.com”

References:

  1. Showraki, Mostafa.  “Autoimmune Disorders”. medicinerevisited.com.
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